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Exclude mapped types with 'as' clauses from certain checks (#47889)
* Exclude mapped types with 'as' clauses from certain checks * Add tests
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6 files changed

+316
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lines changed

6 files changed

+316
-2
lines changed

‎src/compiler/checker.ts

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -12220,6 +12220,7 @@ namespace ts {
1222012220

1222112221
function isMappedTypeGenericIndexedAccess(type: Type) {
1222212222
return type.flags & TypeFlags.IndexedAccess && getObjectFlags((type as IndexedAccessType).objectType) & ObjectFlags.Mapped &&
12223+
!((type as IndexedAccessType).objectType as MappedType).declaration.nameType &&
1222312224
!isGenericMappedType((type as IndexedAccessType).objectType) && isGenericIndexType((type as IndexedAccessType).indexType);
1222412225
}
1222512226

@@ -15656,7 +15657,7 @@ namespace ts {
1565615657
// If the object type is a mapped type { [P in K]: E }, where K is generic, instantiate E using a mapper
1565715658
// that substitutes the index type for P. For example, for an index access { [P in K]: Box<T[P]> }[X], we
1565815659
// construct the type Box<T[X]>.
15659-
if (isGenericMappedType(objectType)) {
15660+
if (isGenericMappedType(objectType) && !objectType.declaration.nameType) {
1566015661
return type[cache] = mapType(substituteIndexedMappedType(objectType, type.indexType), t => getSimplifiedType(t, writing));
1566115662
}
1566215663
return type[cache] = type;
@@ -26650,7 +26651,7 @@ namespace ts {
2665026651

2665126652
function getTypeOfPropertyOfContextualType(type: Type, name: __String, nameType?: Type) {
2665226653
return mapType(type, t => {
26653-
if (isGenericMappedType(t)) {
26654+
if (isGenericMappedType(t) && !t.declaration.nameType) {
2665426655
const constraint = getConstraintTypeFromMappedType(t);
2665526656
const constraintOfConstraint = getBaseConstraintOfType(constraint) || constraint;
2665626657
const propertyNameType = nameType || getStringLiteralType(unescapeLeadingUnderscores(name));

‎tests/baselines/reference/mappedTypeConstraints2.errors.txt

Lines changed: 44 additions & 0 deletions
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@@ -0,0 +1,44 @@
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tests/cases/conformance/types/mapped/mappedTypeConstraints2.ts(10,11): error TS2322: Type 'Mapped2<K>[`get${K}`]' is not assignable to type '{ a: K; }'.
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Type 'Mapped2<K>[`get${string}`]' is not assignable to type '{ a: K; }'.
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tests/cases/conformance/types/mapped/mappedTypeConstraints2.ts(16,11): error TS2322: Type 'Mapped3<K>[Uppercase<K>]' is not assignable to type '{ a: K; }'.
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Type 'Mapped3<K>[string]' is not assignable to type '{ a: K; }'.
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tests/cases/conformance/types/mapped/mappedTypeConstraints2.ts(25,57): error TS2322: Type 'Foo<T>[`get${T}`]' is not assignable to type 'T'.
6+
'T' could be instantiated with an arbitrary type which could be unrelated to 'Foo<T>[`get${T}`]'.
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8+
9+
==== tests/cases/conformance/types/mapped/mappedTypeConstraints2.ts (3 errors) ====
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type Mapped1<K extends string> = { [P in K]: { a: P } };
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function f1<K extends string>(obj: Mapped1<K>, key: K) {
13+
const x: { a: K } = obj[key];
14+
}
15+
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type Mapped2<K extends string> = { [P in K as `get${P}`]: { a: P } };
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function f2<K extends string>(obj: Mapped2<K>, key: `get${K}`) {
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const x: { a: K } = obj[key]; // Error
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~
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!!! error TS2322: Type 'Mapped2<K>[`get${K}`]' is not assignable to type '{ a: K; }'.
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!!! error TS2322: Type 'Mapped2<K>[`get${string}`]' is not assignable to type '{ a: K; }'.
23+
}
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type Mapped3<K extends string> = { [P in K as Uppercase<P>]: { a: P } };
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function f3<K extends string>(obj: Mapped3<K>, key: Uppercase<K>) {
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const x: { a: K } = obj[key]; // Error
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~
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!!! error TS2322: Type 'Mapped3<K>[Uppercase<K>]' is not assignable to type '{ a: K; }'.
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!!! error TS2322: Type 'Mapped3<K>[string]' is not assignable to type '{ a: K; }'.
32+
}
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// Repro from #47794
35+
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type Foo<T extends string> = {
37+
[RemappedT in T as `get${RemappedT}`]: RemappedT;
38+
};
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const get = <T extends string>(t: T, foo: Foo<T>): T => foo[`get${t}`]; // Type 'Foo<T>[`get${T}`]' is not assignable to type 'T'
41+
~~~~~~~~~~~~~~
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!!! error TS2322: Type 'Foo<T>[`get${T}`]' is not assignable to type 'T'.
43+
!!! error TS2322: 'T' could be instantiated with an arbitrary type which could be unrelated to 'Foo<T>[`get${T}`]'.
44+

‎tests/baselines/reference/mappedTypeConstraints2.js

Lines changed: 65 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,65 @@
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//// [mappedTypeConstraints2.ts]
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type Mapped1<K extends string> = { [P in K]: { a: P } };
3+
4+
function f1<K extends string>(obj: Mapped1<K>, key: K) {
5+
const x: { a: K } = obj[key];
6+
}
7+
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type Mapped2<K extends string> = { [P in K as `get${P}`]: { a: P } };
9+
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function f2<K extends string>(obj: Mapped2<K>, key: `get${K}`) {
11+
const x: { a: K } = obj[key]; // Error
12+
}
13+
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type Mapped3<K extends string> = { [P in K as Uppercase<P>]: { a: P } };
15+
16+
function f3<K extends string>(obj: Mapped3<K>, key: Uppercase<K>) {
17+
const x: { a: K } = obj[key]; // Error
18+
}
19+
20+
// Repro from #47794
21+
22+
type Foo<T extends string> = {
23+
[RemappedT in T as `get${RemappedT}`]: RemappedT;
24+
};
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const get = <T extends string>(t: T, foo: Foo<T>): T => foo[`get${t}`]; // Type 'Foo<T>[`get${T}`]' is not assignable to type 'T'
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28+
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//// [mappedTypeConstraints2.js]
30+
"use strict";
31+
function f1(obj, key) {
32+
var x = obj[key];
33+
}
34+
function f2(obj, key) {
35+
var x = obj[key]; // Error
36+
}
37+
function f3(obj, key) {
38+
var x = obj[key]; // Error
39+
}
40+
var get = function (t, foo) { return foo["get".concat(t)]; }; // Type 'Foo<T>[`get${T}`]' is not assignable to type 'T'
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42+
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//// [mappedTypeConstraints2.d.ts]
44+
declare type Mapped1<K extends string> = {
45+
[P in K]: {
46+
a: P;
47+
};
48+
};
49+
declare function f1<K extends string>(obj: Mapped1<K>, key: K): void;
50+
declare type Mapped2<K extends string> = {
51+
[P in K as `get${P}`]: {
52+
a: P;
53+
};
54+
};
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declare function f2<K extends string>(obj: Mapped2<K>, key: `get${K}`): void;
56+
declare type Mapped3<K extends string> = {
57+
[P in K as Uppercase<P>]: {
58+
a: P;
59+
};
60+
};
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declare function f3<K extends string>(obj: Mapped3<K>, key: Uppercase<K>): void;
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declare type Foo<T extends string> = {
63+
[RemappedT in T as `get${RemappedT}`]: RemappedT;
64+
};
65+
declare const get: <T extends string>(t: T, foo: Foo<T>) => T;

‎tests/baselines/reference/mappedTypeConstraints2.symbols

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@@ -0,0 +1,106 @@
1+
=== tests/cases/conformance/types/mapped/mappedTypeConstraints2.ts ===
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type Mapped1<K extends string> = { [P in K]: { a: P } };
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>Mapped1 : Symbol(Mapped1, Decl(mappedTypeConstraints2.ts, 0, 0))
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>K : Symbol(K, Decl(mappedTypeConstraints2.ts, 0, 13))
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>P : Symbol(P, Decl(mappedTypeConstraints2.ts, 0, 36))
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>K : Symbol(K, Decl(mappedTypeConstraints2.ts, 0, 13))
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>a : Symbol(a, Decl(mappedTypeConstraints2.ts, 0, 46))
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>P : Symbol(P, Decl(mappedTypeConstraints2.ts, 0, 36))
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function f1<K extends string>(obj: Mapped1<K>, key: K) {
11+
>f1 : Symbol(f1, Decl(mappedTypeConstraints2.ts, 0, 56))
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>K : Symbol(K, Decl(mappedTypeConstraints2.ts, 2, 12))
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>obj : Symbol(obj, Decl(mappedTypeConstraints2.ts, 2, 30))
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>Mapped1 : Symbol(Mapped1, Decl(mappedTypeConstraints2.ts, 0, 0))
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>K : Symbol(K, Decl(mappedTypeConstraints2.ts, 2, 12))
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>key : Symbol(key, Decl(mappedTypeConstraints2.ts, 2, 46))
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>K : Symbol(K, Decl(mappedTypeConstraints2.ts, 2, 12))
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const x: { a: K } = obj[key];
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>x : Symbol(x, Decl(mappedTypeConstraints2.ts, 3, 9))
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>a : Symbol(a, Decl(mappedTypeConstraints2.ts, 3, 14))
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>K : Symbol(K, Decl(mappedTypeConstraints2.ts, 2, 12))
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>obj : Symbol(obj, Decl(mappedTypeConstraints2.ts, 2, 30))
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>key : Symbol(key, Decl(mappedTypeConstraints2.ts, 2, 46))
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}
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type Mapped2<K extends string> = { [P in K as `get${P}`]: { a: P } };
28+
>Mapped2 : Symbol(Mapped2, Decl(mappedTypeConstraints2.ts, 4, 1))
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>K : Symbol(K, Decl(mappedTypeConstraints2.ts, 6, 13))
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>P : Symbol(P, Decl(mappedTypeConstraints2.ts, 6, 36))
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>K : Symbol(K, Decl(mappedTypeConstraints2.ts, 6, 13))
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>P : Symbol(P, Decl(mappedTypeConstraints2.ts, 6, 36))
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>a : Symbol(a, Decl(mappedTypeConstraints2.ts, 6, 59))
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>P : Symbol(P, Decl(mappedTypeConstraints2.ts, 6, 36))
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function f2<K extends string>(obj: Mapped2<K>, key: `get${K}`) {
37+
>f2 : Symbol(f2, Decl(mappedTypeConstraints2.ts, 6, 69))
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>K : Symbol(K, Decl(mappedTypeConstraints2.ts, 8, 12))
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>obj : Symbol(obj, Decl(mappedTypeConstraints2.ts, 8, 30))
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>Mapped2 : Symbol(Mapped2, Decl(mappedTypeConstraints2.ts, 4, 1))
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>K : Symbol(K, Decl(mappedTypeConstraints2.ts, 8, 12))
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>key : Symbol(key, Decl(mappedTypeConstraints2.ts, 8, 46))
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>K : Symbol(K, Decl(mappedTypeConstraints2.ts, 8, 12))
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const x: { a: K } = obj[key]; // Error
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>x : Symbol(x, Decl(mappedTypeConstraints2.ts, 9, 9))
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>a : Symbol(a, Decl(mappedTypeConstraints2.ts, 9, 14))
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>K : Symbol(K, Decl(mappedTypeConstraints2.ts, 8, 12))
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>obj : Symbol(obj, Decl(mappedTypeConstraints2.ts, 8, 30))
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>key : Symbol(key, Decl(mappedTypeConstraints2.ts, 8, 46))
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}
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type Mapped3<K extends string> = { [P in K as Uppercase<P>]: { a: P } };
54+
>Mapped3 : Symbol(Mapped3, Decl(mappedTypeConstraints2.ts, 10, 1))
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>K : Symbol(K, Decl(mappedTypeConstraints2.ts, 12, 13))
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>P : Symbol(P, Decl(mappedTypeConstraints2.ts, 12, 36))
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>K : Symbol(K, Decl(mappedTypeConstraints2.ts, 12, 13))
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>Uppercase : Symbol(Uppercase, Decl(lib.es5.d.ts, --, --))
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>P : Symbol(P, Decl(mappedTypeConstraints2.ts, 12, 36))
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>a : Symbol(a, Decl(mappedTypeConstraints2.ts, 12, 62))
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>P : Symbol(P, Decl(mappedTypeConstraints2.ts, 12, 36))
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function f3<K extends string>(obj: Mapped3<K>, key: Uppercase<K>) {
64+
>f3 : Symbol(f3, Decl(mappedTypeConstraints2.ts, 12, 72))
65+
>K : Symbol(K, Decl(mappedTypeConstraints2.ts, 14, 12))
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>obj : Symbol(obj, Decl(mappedTypeConstraints2.ts, 14, 30))
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>Mapped3 : Symbol(Mapped3, Decl(mappedTypeConstraints2.ts, 10, 1))
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>K : Symbol(K, Decl(mappedTypeConstraints2.ts, 14, 12))
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>key : Symbol(key, Decl(mappedTypeConstraints2.ts, 14, 46))
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>Uppercase : Symbol(Uppercase, Decl(lib.es5.d.ts, --, --))
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>K : Symbol(K, Decl(mappedTypeConstraints2.ts, 14, 12))
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const x: { a: K } = obj[key]; // Error
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>x : Symbol(x, Decl(mappedTypeConstraints2.ts, 15, 9))
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>a : Symbol(a, Decl(mappedTypeConstraints2.ts, 15, 14))
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>K : Symbol(K, Decl(mappedTypeConstraints2.ts, 14, 12))
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>obj : Symbol(obj, Decl(mappedTypeConstraints2.ts, 14, 30))
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>key : Symbol(key, Decl(mappedTypeConstraints2.ts, 14, 46))
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}
80+
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// Repro from #47794
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type Foo<T extends string> = {
84+
>Foo : Symbol(Foo, Decl(mappedTypeConstraints2.ts, 16, 1))
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>T : Symbol(T, Decl(mappedTypeConstraints2.ts, 20, 9))
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[RemappedT in T as `get${RemappedT}`]: RemappedT;
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>RemappedT : Symbol(RemappedT, Decl(mappedTypeConstraints2.ts, 21, 5))
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>T : Symbol(T, Decl(mappedTypeConstraints2.ts, 20, 9))
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>RemappedT : Symbol(RemappedT, Decl(mappedTypeConstraints2.ts, 21, 5))
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>RemappedT : Symbol(RemappedT, Decl(mappedTypeConstraints2.ts, 21, 5))
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};
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const get = <T extends string>(t: T, foo: Foo<T>): T => foo[`get${t}`]; // Type 'Foo<T>[`get${T}`]' is not assignable to type 'T'
96+
>get : Symbol(get, Decl(mappedTypeConstraints2.ts, 24, 5))
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>T : Symbol(T, Decl(mappedTypeConstraints2.ts, 24, 13))
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>t : Symbol(t, Decl(mappedTypeConstraints2.ts, 24, 31))
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>T : Symbol(T, Decl(mappedTypeConstraints2.ts, 24, 13))
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>foo : Symbol(foo, Decl(mappedTypeConstraints2.ts, 24, 36))
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>Foo : Symbol(Foo, Decl(mappedTypeConstraints2.ts, 16, 1))
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>T : Symbol(T, Decl(mappedTypeConstraints2.ts, 24, 13))
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>T : Symbol(T, Decl(mappedTypeConstraints2.ts, 24, 13))
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>foo : Symbol(foo, Decl(mappedTypeConstraints2.ts, 24, 36))
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>t : Symbol(t, Decl(mappedTypeConstraints2.ts, 24, 31))
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‎tests/baselines/reference/mappedTypeConstraints2.types

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=== tests/cases/conformance/types/mapped/mappedTypeConstraints2.ts ===
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type Mapped1<K extends string> = { [P in K]: { a: P } };
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>Mapped1 : Mapped1<K>
4+
>a : P
5+
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function f1<K extends string>(obj: Mapped1<K>, key: K) {
7+
>f1 : <K extends string>(obj: Mapped1<K>, key: K) => void
8+
>obj : Mapped1<K>
9+
>key : K
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const x: { a: K } = obj[key];
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>x : { a: K; }
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>a : K
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>obj[key] : Mapped1<K>[K]
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>obj : Mapped1<K>
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>key : K
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}
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type Mapped2<K extends string> = { [P in K as `get${P}`]: { a: P } };
20+
>Mapped2 : Mapped2<K>
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>a : P
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function f2<K extends string>(obj: Mapped2<K>, key: `get${K}`) {
24+
>f2 : <K extends string>(obj: Mapped2<K>, key: `get${K}`) => void
25+
>obj : Mapped2<K>
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>key : `get${K}`
27+
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const x: { a: K } = obj[key]; // Error
29+
>x : { a: K; }
30+
>a : K
31+
>obj[key] : Mapped2<K>[`get${K}`]
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>obj : Mapped2<K>
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>key : `get${K}`
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}
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type Mapped3<K extends string> = { [P in K as Uppercase<P>]: { a: P } };
37+
>Mapped3 : Mapped3<K>
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>a : P
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function f3<K extends string>(obj: Mapped3<K>, key: Uppercase<K>) {
41+
>f3 : <K extends string>(obj: Mapped3<K>, key: Uppercase<K>) => void
42+
>obj : Mapped3<K>
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>key : Uppercase<K>
44+
45+
const x: { a: K } = obj[key]; // Error
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>x : { a: K; }
47+
>a : K
48+
>obj[key] : Mapped3<K>[Uppercase<K>]
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>obj : Mapped3<K>
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>key : Uppercase<K>
51+
}
52+
53+
// Repro from #47794
54+
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type Foo<T extends string> = {
56+
>Foo : Foo<T>
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58+
[RemappedT in T as `get${RemappedT}`]: RemappedT;
59+
};
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const get = <T extends string>(t: T, foo: Foo<T>): T => foo[`get${t}`]; // Type 'Foo<T>[`get${T}`]' is not assignable to type 'T'
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>get : <T extends string>(t: T, foo: Foo<T>) => T
63+
><T extends string>(t: T, foo: Foo<T>): T => foo[`get${t}`] : <T extends string>(t: T, foo: Foo<T>) => T
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>t : T
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>foo : Foo<T>
66+
>foo[`get${t}`] : Foo<T>[`get${T}`]
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>foo : Foo<T>
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>`get${t}` : `get${T}`
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>t : T
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‎tests/cases/conformance/types/mapped/mappedTypeConstraints2.ts

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// @strict: true
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// @declaration: true
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type Mapped1<K extends string> = { [P in K]: { a: P } };
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function f1<K extends string>(obj: Mapped1<K>, key: K) {
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const x: { a: K } = obj[key];
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}
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type Mapped2<K extends string> = { [P in K as `get${P}`]: { a: P } };
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function f2<K extends string>(obj: Mapped2<K>, key: `get${K}`) {
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const x: { a: K } = obj[key]; // Error
14+
}
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type Mapped3<K extends string> = { [P in K as Uppercase<P>]: { a: P } };
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function f3<K extends string>(obj: Mapped3<K>, key: Uppercase<K>) {
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const x: { a: K } = obj[key]; // Error
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}
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// Repro from #47794
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24+
type Foo<T extends string> = {
25+
[RemappedT in T as `get${RemappedT}`]: RemappedT;
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};
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const get = <T extends string>(t: T, foo: Foo<T>): T => foo[`get${t}`]; // Type 'Foo<T>[`get${T}`]' is not assignable to type 'T'

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